The disclosed subject matter relates to a network system providing stable services in response to a service request from a client terminal.
In an IP network environment, there exists a technique known as DNS round robin for causing plural server apparatuses present in a domain name system (DNS) to be disguised as a single server for each client terminal in a virtual manner, the DNS being used to perform name resolution processing from the client terminals to the server apparatuses. The technique further operates to distribute the server load.
Furthermore, a DNS system technique described in U.S. Pat. No. 7,284,051, is available as a technique that has expanded the DNS round robin technique. In particular, a DNS server monitors how each server apparatus is loaded and sends back the IP addresses of lightly loaded server apparatuses as responses.
This US patent states that “A relaying apparatus comprises a client terminal, many server terminals connected via network to the client terminal, a DNS responding device which accepts a DNS inquiry from the client terminal via a client-side DNS device, and one path load measuring device for each of the server terminals which measures a load in the communication path up to the client-side DNS device. The DNS responding device distributes a work load by routing a service request from the client terminal to any one of the server terminals based on the measurement result (i.e. route load)” (abstract).